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本区经历四期变质作用,太古宙上壳岩系麻粒岩相变质、晚太古宙英云闪长岩高角闪岩相变质、早元古宙紫苏花岗岩类低角闪岩相变质和元古宙绿片岩相变质。麻粒岩相变质期可分三个阶段,早期角闪岩相、峰期麻粒岩相和晚期角闪岩相,其P-T-t轨迹为逆时针,与IBC型轨迹相似。导致麻粒岩相变质作用的热源为英云闪长质岩浆的垫托作用,形成于岛弧或活动大陆边缘。区内广泛发育的钾长花岗岩与晚太古宙高角闪岩相变质作用晚期的深熔作用有关。 相似文献
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冀东地区麻粒岩相变质作用的演化 总被引：1，自引：2，他引：1
据冀东迁安－遵化一带麻粒岩相区的变质岩石、变质矿物及其组构特征、变质作用的温度、压力条件，结合同位素年代学资料，以及岩浆作用、构造变形作用和变质作用之间的关系，可将本区太古代变质作用划分为两期。太古代第一期变质作用只限于表壳岩包体岩石中，变质级为高角闪岩相和辉石麻粒岩相，第二期变质作用发生在晚太古代，早期变质阶段是在紫苏花岗岩侵位以后发生的辉石麻粒岩相变质作用，晚期变质阶段发生在稍后侵位的基性侵入岩体、英云闪长岩、奥长花岗岩等深成侵入体中，变质级达角闪麻粒岩相。早元古代第一期角闪石榴二辉麻粒岩型岩脉，遭受了辉石麻粒相变质作用，第二期角闪石榴斜长辉石岩型岩脉经历了角闪麻粒岩相变质作用。这些变质作用在早期岩石中都有不同程度的叠加。麻粒岩相变质作用的温度在７００℃～９２０℃，压力在０．８８～１．１４ＧＰａ。变质作用的ＰＴｔ演化呈现了逆时针近等压冷却的轨迹 相似文献
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通过对山东沂水地区紫苏花岗岩野外地质特征、岩相学及地球化学特征等的研究,认为山东沂水地区紫苏花岗岩为变质表壳岩经深熔作用形成．其主要证据为：（１）紫苏花岗岩与变质表壳岩在空间上密切伴生,二者多为渐变过渡接触关系,且他们的片麻理协调一致;（２）在变质表壳岩中发育大量长英质或花岗质脉体,这些脉体的矿物成分、地球化学特征与紫苏花岗岩一致;（３）紫苏花岗岩与变质表壳岩具有相似的稀土配分型式;（４）紫苏花岗岩亏损大离子亲石元素及生热元素,其原岩应为经历了深变质作用的岩石;（５）紫苏花岗岩中锆石多为圆粒状和椭球状,并发育磨蚀坑,说明其原岩主要为变沉积岩;（６）麻粒岩相变质作用时间与紫苏花岗岩形成时间基本一致． 相似文献
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胶东东部地区元古宙花岗岩类的地球化学及岩石成因 总被引：4，自引：3，他引：4
胶东东部地区的元古宙花岗岩－片麻岩杂岩，可分为：（１）石英闪长质－英云闪长质－花岗闪长质片麻岩、（２）二长花岗质－钾长花岗质片麻岩和（３）淡色花岗岩三套岩石。它们之间可识别侵位先后关系，岩相中普遍存在残留的斜长石板状晶体、并具环带结构为主的原生深成岩的矿物相组构，地球化学成分演化各具独立性，并具有深熔花岗岩的性质，结合同位素年龄资料，确立它们是元古宙不同造山阶段形成的花岗岩。岩石中普遍存在Ｔｉ、Ｙ、Ｓｒ、Ｎｉ及Ｍｇ等元素的强烈亏损，表明岩浆来源并非直接来源于上地幔或下地壳，它们是元古宙不同阶段已形成的岩石发生深熔作用形成的。这一认识有助于了解华北地台南缘东段元古宙这一重要地质时期的地壳形成和演化。 相似文献
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山东沂水紫苏花岗岩中残晶相矿物的发现及紫苏花岗岩的形成过程 总被引：4，自引：0，他引：4
山东沂水地区紫苏花岗岩主要有 3种类型 ,分别为紫苏花岗闪长岩、紫苏石榴花岗闪长岩和紫苏奥长花岗岩。紫苏花岗岩中普遍存在有熔体交代结构 ,主要由残晶相矿物和结晶相矿物组成。对紫苏花岗岩及变质表壳中流体包裹体产状、成分的研究发现 ,富CO2 流体包裹体和富N2 流体包裹体均来自地幔深部。紫苏花岗岩的形成过程如下 :基性岩浆的底侵作用使本区经历了第一期麻粒岩相变质作用 ,地幔富CO2 流体包裹体的存在使系统a(H2 O)很低 (a(H2 O) =0 .1～ 0 .3) ,麻粒岩相变质作用没有产生熔融作用。幔源岩浆活动的逐渐停止 ,该区又经历了近等压降温的第二期麻粒岩相变质作用。此时 ,深源富CO2 流体作用减弱 ,水的活度增加 ,a(H2 O) =0 .6 5～ 0 .75 ,从而产生岩浆 ,新生岩浆对早期形成的变质矿物进行熔蚀交代作用 ,使早期形成的难熔变质矿物如紫苏辉石、石榴石、单斜辉石等呈残晶相 ,随着温度的降低岩浆基本在原地半原地结晶形成紫苏花岗岩。 相似文献
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天镇—怀安地区早前寒武纪钾质花岗岩地球化学特征及构造环境 总被引：2，自引：0，他引：2
晋冀内蒙古交界地区太古宙怀安杂岩以南发育一条花岗岩带，和怀安杂岩以高压麻粒岩混杂岩带相隔，是该区一个单独的岩石构造单元，规模较大，宽２０多ｋｍ。从山西繁峙白马石经天镇南部向北东一直到宣化西葛峪和二道岭，断续相连。北东东向延伸近２００ｋｍ，延伸方向与区域片麻理和主构造线方向一致。该花岗岩带由众多中小规模花岗岩侵入体和其间残留体组成。大部分花岗岩呈肉红色，以富钾质和含有高压基性麻粒岩包体为特征，许多花岗岩发育片麻构造。岩石学研究表明，大多数花岗岩经历了变质作用，一些花岗岩经历了麻粒岩相变质作用，具有麻粒岩相矿物组合Ｑ＋Ｐｅｒ＋Ｐｌ±Ｇｔ＋Ｂｉ（棕）±Ｈｂ＋Ｍｔ，石榴石、黑云母等矿物的成分显示出麻粒岩相变质的特征。大部分花岗岩都是近低熔花岗岩的组分，并显示某些钙碱性岩系的演化趋势。微量元素组成表现出较大的变化范围，多数花岗岩富Ｋ，Ｒｂ，Ｂａ，贫Ｚｒ，Ｙ，Ｙｂ，部分样品还亏损Ｔｈ，Ｔａ和Ｎｂ，稀土元素从低到高有４种不同的配分型式。这些花岗岩由许多不同类型源岩的部分熔融形成，具有与碰撞型花岗岩相似的常量和微量元素地球化学性质。锆石Ｕ－Ｐｂ一致线年龄为２３７０Ｍａ，指示出这些花岗岩形成于太古宙末期。这条花岗岩带有可能是 相似文献
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吉林南部太古宙辉石花岗岩的成因 总被引：1，自引：0，他引：1
吉林南部太古宙辉石花岗岩类具有与英云闪长质－奥长花岗岩质－花岗闪长质片麻岩（ＴＴＧ）及深熔钾长花岗岩不同的特征，并不是ＴＴＧ岩系的一部分。地质学、岩石学及地球化学研究表明，该辉石花岗岩类是壳源岩浆结晶分异作用的结果，其岩浆演化主要受早期结晶的辉石、斜长石及角闪石等矿物相的制约。 相似文献
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内蒙大青山早前寒武纪变质岩和早期陆壳的演化 总被引：1，自引：0，他引：1
将大青山地区早前寒武纪变质岩石分成三个岩性构造组合.即(1)麻粒岩—紫苏花岗岩组合;(2)角闪片麻岩—英云闪长岩组合;(3)富铝片麻岩—钾质花岗岩组合.其中,组合(1)是区内最古老的物质组成,其形成时代至少应在晚太古代以前(>2800Ma).组合(2)是具花岗—绿岩带特征的晚太古代中、低级变质岩系.组合(3)是经早元古造山变质作用形成的岩石组合.根据重新排定的地质事件顺序,对本区早期地壳演化的有关问题进行了讨论. 相似文献
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Emily Keeble David I. Whiteside Michael J. Benton 《Proceedings of the Geologists' Association. Geologists' Association》2018,129(2):99-119
Pant-y-ffynnon Quarry in South Wales yielded a rich cache of fossils in the early 1950s, including articulated specimens of new species (the small sauropodomorph dinosaur Pantydraco caducus and the crocodylomorph Terrestrisuchus gracilis), but no substantial study of the wider fauna of the Pant-y-ffynnon fissure systems has been published. Here, our overview of existing specimens, a few described but mostly undescribed, as well as freshly processed material, provides a comprehensive picture of the Pant-y-ffynnon palaeo-island of the Late Triassic. This was an island with a relatively impoverished fauna dominated by small clevosaurs (rhynchocephalians), including a new species, Clevosaurus cambrica, described here from a partially articulated specimen and isolated bones. The new species has a dental morphology that is intermediate between the Late Triassic Clevosaurus hudsoni, from Cromhall Quarry to the east, and the younger C. convallis from Pant Quarry to the west, suggesting adaptive radiation of clevosaurs in the palaeo-archipelago. The larger reptiles on the palaeo-island do not exceed 1.5?m in length, including a small carnivorous crocodylomorph, Terrestrisuchus, and a possible example of insular dwarfism in the basal dinosaur Pantydraco. 相似文献
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Gilles Serge Odin 《Comptes Rendus Geoscience》2002,334(6):409-414
Lithostratigraphy, physicochemical stratigraphy, biostratigraphy, and geochronology of the 77–70 Ma old series bracketing the Campanian–Maastrichtian boundary have been investigated by 70 experts. For the first time, direct relationships between macro- and microfossils have been established, as well as direct and indirect relationships between chemo-physical and biostratigraphical tools. A combination of criteria for selecting the boundary level, duration estimates, uncertainties on durations and on the location of biohorizons have been considered; new chronostratigraphic units are proposed. The geological site at Tercis is accepted by the Commission on Stratigraphy as the international reference for the stratigraphy of the studied interval. To cite this article: G.S. Odin, C. R. Geoscience 334 (2002) 409–414. 相似文献
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The effect of water on accessory phase solubility in subaluminous and peralkaline granitic melts 总被引：4，自引：0，他引：4
The solubilities of columbite, tantalite, wolframite, rutile, zircon and hafnon were determined as a function of the water contents in peralkaline and subaluminous granite melts. All experiments were conducted at 1035 °C and 2 kbar and the water contents of the melts ranged from nominally dry to approximately 6 wt.% H2O. Accessory phase solubilities are not affected by the water content of the peralkaline melt. By contrast, solubilities are affected by the water content of the subaluminous melt, where the solubilities of all the accessory phases examined increase with the water content of the melt, up to 2 wt.% H2O. At higher water contents, solubilities are nearly constant. It can be concluded that water is not an important control of accessory phase solubility, although the water content will affect diffusivities of components in the melt, thus whether or not accessory phases will be present as restite material. The solubility behaviour in the subaluminous and peralkaline melts supports previous spectroscopic studies, which have observed differences in the coordination of high field strength elements in dry vs. wet subaluminous granitic glasses, but not for peralkaline granitic glasses. Lastly, the fact that wolframite solubility increases with increasing water content in the subaluminous melt suggests that tungsten dissolved as a hexavalent species. 相似文献
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Emmanuel Skourtsos Daniel Vachard Alexandra Zambetakis-Lekkas Rossana Martini Louisette Zaninetti 《Comptes Rendus Geoscience》2002,334(12):925-931
Some olistolites reworked in a Tertiary flysch of Mount Parnon (Peloponnesus, Greece) exhibit a Late Permian assemblage, dominated by Paradunbarula (Shindella) shindensis, Hemigordiopsis cf. luquensis and Colaniella aff. minima. This association corresponds to the Late Wuchiapingian (=Late Dzhulfian), a substage whose algae and foraminifera are generally little known. Contemporaneous limestones crop out in the middle part of the Episkopi Formation in Hydra, but they are rather commonly reworked in Mesozoic and Cainozoic sequences. The palaeobiogeographical affinities shared by the foraminiferal markers of Greece, southeastern Pamir, and southern China, are very strong (up to the specific level), and are congruent with the Pangea B reconstructions. To cite this article: E. Skourtsos et al., C. R. Geoscience 334 (2002) 925–931. 相似文献
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正20141596 Liu Yunhuan(School of Earth Sciences and Resources,Chang’an University,Xi’an 710054,China);Shao Tiequan Early Cambrian Quadrapyrgites Fossils of Xixiang Boita in Southern Shaanxi Province(Journal of Earth Sciences and Environment,ISSN1672-6561,CN61-1423/P,35(3),2013,p.39-43,3 illus.,20 refs.) 相似文献
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正20141719 Chen Zhijun(State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan 430074,China);Chen Jianguo Automated Batch Mapping Solution for Serial Maps:A Case Study of Exploration Geochemistry Maps(Journal of Geology,ISSN1674-3636,CN32-1796/P,37(3),2013,p.456-464,2 illus.,2 tables,10 refs.) 相似文献
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正20140962 Chen Fenning(Xi’an Institute of Geology and Mineral Resources,Xi’an710054,China);Chen Ruiming Late Miocene-Early Pleistocene Ostracoda Fauna of Gyirong Basin,Southern Tibet(Acta Geologica Sinica,ISSN0001-5717,CN11-1951/P,87(6),2013,p.872-886,6illus.,56refs.) 相似文献
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正1.IGNEOUS PETROLOGY20142008Cai Jinhui(Wuhan Center,China Geological Survey,Wuhan 430205,China);Liu Wei Zircon U-Pb Geochronology and Mineralization Significance of Granodiorites from Fuzichong Pb-Zn Deposit,Guangxi,South China(Geology and Mineral Resources of South China,ISSN1007-3701,CN42-1417/P,29(4),2013,p.271-281,7illus., 相似文献
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正20141205Cheng Weiming(State Key Laboratory of Resources and Environmental Information System,Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China);Xia Yao Regional Hazard Assessment of Disaster Environment for Debris Flows:Taking Jundu Mountain,Beijing as an 相似文献